1. Field of the Invention
The present invention relates to a device for separating and stacking blanks such as box blanks and more particularly to a device which is adapted to receive sheets containing a plurality of interconnected blanks which are received from a platen press and to separate the interconnected blanks and stack them in predetermined or designated stacks.
2. Prior Art
The platen presses which have been used in the past to produce box blanks or carton blanks have been of two general types. The first type uses individual sheets for each of the blanks to be produced and the output of this type of press consists of individual blanks which may be conveniently formed into a stack. The second type of press simultaneously produces a plurality of interconnected blanks in a sheet which may be preprinted with the printed matter for each of the cartons or boxes. The press processes the sheet to remove the scrap and waste material and the output of the press consists of a sheet formed of a plurality of interconnected box blanks which are free from scrap and the waste material. These sheets may be stacked individually, but it is thereafter necessary to separate the individual blanks before they can be arranged into individual stacks for later handling or processing.
While the first type of machine produces a single stack of individual box blanks, it is relatively slow in terms of output per unit time. The second type of machine has a faster output but the manual labor required to separate the interconnected blanks is a drawback which detracts from its efficiency. For example, a stack of the sheets having interconnected blanks are manually separated by using either air chisels or hammers and chisels. Such manual operations are extremely noisy and are expensive due to the labor cost involved. In addition thereto, misalignment of the separating tool such as the chisel can cause cuts or damage to the edges of the blanks which cuts or damage interfere with subsequent processing of the blank into a box or carton.
When die cutting blanks for boxes or cartons in a preprinted sheet, the interconnected blanks in each sheet which are formed by the press operations may be for cartons or boxes for different products even though the size of each of the blanks formed in the sheet may be the same. Thus, since the interconnected blanks in the sheet may be for different products, it is desirable during separation of the blanks that the individual blank from each position in the sheet of interconnected blanks be maintained separately from adjacent blanks to prevent intermixing of blanks which were printed for different products.
A separating and stacking machine which would handle a sheet of interconnected blanks with the blanks arranged in rows is disclosed in U.S. Pat. No. 3,870,213 which was issued on Mar. 11, 1975. In this machine, the sheet of interconnected blanks is carried by an input conveyor to a separating unit which separates the interconnected blanks into individual blanks to create a flow of space side-by-side rows of spaced blanks which are received by a stacking unit having a conveyor system of sets of rollers and upper lower castors. One pair of rollers and castors of each set is designated so that the point of engagement of the upper roller or castor can be shifted on the circumference of the lower roller to apply a deflecting force to a blank passing therethrough to cause the blank to be deflected into a storage compartment or stack receiving means. However, this device has some problems and has not proven to be completely satisfactory during operation. For example, the deflecting force caused by the roller arrangement causes the blank to bend partially around the circumference of the lower roller and imparts a curve or bend in the blank. The curve or bend in the blank impairs the dropping of the blank into the stack.